One-dimensional nanostructure based chemiresistive sensors have received great attention because of their compact design and excellent sensing performance including high sensitivity, low detection limits, low power consumption, and ability to integrate multi-sensor arrays. However, these sensors can suffer from slow response and recovery times when it operated at ambient conditions because of slow catalytic or absorption/desorption processes. The sensors can overcome these obstacles by operating at high temperature, which can increase device complexity with higher power consumption rate.
Over the past few decades, the detection of nitrogen dioxide (NO2) in combustion exhaust or in the environment has been of significant interest because the presence of NO2 has been correlated to the formation of acid rain, photochemical smog and some respiratory diseases including emphysema and bronchitis. Several types of NO2 sensors have been developed including chemiresistive, potentiometric, and amperometric, based on metal oxides (for example, WO3, SnO2, ZnO, NiO and ZrO2). Within the realm of gas sensing, chemiresistive metal oxide sensors have dominated the field because of their robust nature and simple circuit design. However, metal oxide based sensors can require high operating temperature in order to obtain decent sensitivities and faster response/recovery times. This feature can significantly reduce selectivity as many analytes interact with oxide surface, while also increasing power consumption and device complexity. In fact, temperature control systems can overshadow both operating costs and design of the actual sensing element and have been the focus of several nanostructured gas sensor platforms, which have demonstrated advanced thermal control architectures through a series of lithographical fabrication steps. Consequently, facile approaches to rapid, reversible and selective chemical detection at room temperature can provide substantial gains in terms of cost and manufacturability to facilitate massive deployment or smart sensor arrays essential for environmental monitoring and medical diagnosis.